Efficient All‐Polymer Photomultiplication‐Type Organic Photodetectors with Prolonged Crystallization Process

Abstract With the progressive development of photomultiplication‐type organic photodetectors (PM‐OPDs), increasing research efforts are devoted to all‐polymer PM‐OPDs due to their potential in terms of device stability and stretchability. However, poor polymer‐polymer miscibility and entanglement of long polymer chains are still the main challenges to form desirable active layer morphology in such systems. A smooth solidification process is favorable toward realizing a morphology that features ordered molecular orientation and high crystallinity. Herein, morphological control issue in all‐polymer PM‐OPDs is addressed by modifying film formation kinetics with an insulating polymer blending strategy. The prolonged crystallization process of polystyrene‐blended films can form high‐ordered molecular arrangements and crystallinity in donor/acceptor phases, leading to improved charge transport properties and suppressed trap states. With boosting the trap‐assisted photomultiplication effect, the polystyrene‐blended all‐polymer PM‐OPD with a high specific detectivity of 4.0 × 10¹³ Jones can be achieved due to the accumulation of enhanced photogenerated electrons at the interface and the efficient injection of external holes, which is one of the best detectivity values reported for PM‐OPDs. This study not only reveals valuable insights into the effects of insulating polymers on the film formation kinetics mechanism, but also provides novel strategy to fabricate high‐performance all‐polymer PM‐OPDs.